Table 1.

Data characteristics of lung sound clips in the training and internal validation set and the prospective validation set.

Training and internal validation set	Normal	Crackles	Wheezing	Total
	(n = 288)	(n = 200)	(n = 192)	(N = 680)
Length of clip (s)	4.7 ± 1.8	4.3 ± 1.7	3.1 ± 1.2	4.1 ± 1.8
Number of breath cycles
1 cycle	3 (11.1%)	42 (21.0%)	64 (33.3%)	138 (20.3%)
2 cycles	256 (88.9%)	158 (79.0%)	128 (66.7%)	542 (79.7%)
Respiratory rate (/min)	27.3 ± 10.2	28.4 ± 12.3	36.4 ± 16.5	30.2 ± 13.4
Heart sound
Inaudible	71 (24.7%)	49 (24.5%)	50 (26.0%)	170 (25.0%)
Normal	217 (75.3%)	151 (75.5%)	142 (74.0%)	510 (75.0%)

Prospective validation set	Normal	Crackle	Wheezing	Total
	(n = 28)	(n = 31)	(n = 31)	(N = 90)
Length of clip (s)	4.9 ± 1.6	4.0 ± 1.2	3.3 ± 1.2	4.0 ± 1.5
Number of breath cycles
1 cycle	2 (7.1%)	13 (41.9%)	15 (48.4%)	30 (33.3%)
2 cycles	26 (92.9%)	18 (58.1%)	16 (51.6%)	60 (66.7%)
Respiratory rate (/min)	26.1 ± 8.5	24.6 ± 6.1	30.8 ± 13.0	27.2 ± 9.9
Heart sound
Inaudible	3 (10.7%)	0 (0.0%)	2 (6.5%)	5 (5.6%)
Normal	25 (89.3%)	31 (100.0%)	29 (93.5%)	85 (94.4%)